The general aim of this proposed experimental investigation is to determine the fundamental principles of molecular structure and dynamics that are responsible for efficient intra- and inter-protein electron transfer reactions. This will require identification of the parameters (e.g. structures of redox states, dynamics, solvent reorganization energies, etc.) governing electron transfer rates, directional specificity, and successful charge separation reactions. Questions aimed at testing these architectural characteristics of natural, electron transfer proteins will be addressed using novel synthetic constructs of protein plus cofactors, called maquettes, designed to provide minimal protein structures that mimic key electron transfer function of their natural in vivo protein counterparts. Initial emphasis will involve modeling key electron transfer components of the cytochrome bc1 complex. Using advanced solution nmr techniques as the primary tool in this effort, we will examine the structural and dynamic contributions to stability of the maquettes and to the electron transfer properties of the heme prothetic groups bound to the model protein.